PDA

View Full Version : My favorite computer



squirrel-steam
June 11th, 2008, 03:10 PM
Is this - Im pretty sure its a DEC (says digital equipment corporation on the front in the picture,) does anyone happen to have one of these beauties? Know the specs, how you work with it? etc...

http://i143.photobucket.com/albums/r157/squirrelguy_2007/DECPDP-8.jpg

ahm
June 11th, 2008, 05:00 PM
It's a DEC PDP-8. Many models were made. The one in the picture is known as a "straight 8".

Our club, MARCH, just rescued one in April.
Photos can be found here, http://vintagecomputer.net/tcf_2008/ (billdeg's website)

Plenty of info, here:
http://en.wikipedia.org/wiki/Pdp8

Druid6900
June 11th, 2008, 08:10 PM
It's a DEC PDP-8. Many models were made. The one in the picture is known as a "straight 8".

Our club, MARCH, just rescued one in April.
Photos can be found here, http://vintagecomputer.net/tcf_2008/ (billdeg's website)

Plenty of info, here:
http://en.wikipedia.org/wiki/Pdp8

Was it at the bottom of a river in the Netherlands, holding a houseboat down? :)

ahm
June 12th, 2008, 03:30 AM
Was it at the bottom of a river in the Netherlands, holding a houseboat down? :)
Not quite. It was in a barn for many years. That's why we found an old mouse nest inside.

Jorg
June 12th, 2008, 03:49 AM
Was it at the bottom of a river in the Netherlands, holding a houseboat down? :)

LOL, exactly what I was thinking..

erd
June 13th, 2008, 07:01 PM
Is this - Im pretty sure its a DEC (says digital equipment corporation on the front in the picture,) does anyone happen to have one of these beauties? Know the specs, how you work with it? etc...

It's an original model PDP-8, also called a "Straight-8" (as opposed to an -8/S, -8/i, -8/L...)

Without any expansion, it's a 4Kword machine with, IIRC, a TTY interface, and that's it. There were a number of peripherals for it including fixed-head disks (the platter rotates just like a modern hard disk, but there are several dozen read/write heads that are bolted to the undercarriage) and random access tape (imagine a floppy disk with all the sectors lined up one after the other). You work with it the same way you work with later models - toggle in whole programs, or, when that gets tiring, a bootstrap to read in paper tapes or an operating system if you have disk or tape.

I happen to have two of these, but rack-mount, not the sexy desktop model in the picture. I also have some DF32 disk drives (the type mentioned above). Unfortunately, mine were used in a print shop and are covered with printers ink, so I have yet to power either of them up. I also have several examples of more modern PDP-8s that do work just fine.

The PDP-8 processor was sold, in one form or another, from the transistor era up through VLSI microprocessors (Intersil/Harris IM-6120), spanning about 30 years from about 1964 to 1994 (Straight-8 through DECmate III+). There was even a PDP-8 clone sold for a few years recently called the SBC-6120 (single-board computer w/IM-6120) with an optional front panel and rare FPGA-based I/O expansion board (IOB6120). The primary OS for machines with at least 8K and a random-access device is OS/8. AFAIK, as long as you have the required memory and disk/tape, OS/8 will run on all models of PDP-8 (the minor exception being console I/O differences with DECmates, requiring a slightly modified version called OS/78 or OS/278). I've never tried running OS/8 on anything older than a PDP-8/e, but only because none of my older machines have enough memory or have a disk.

There's something striking about the old modular CPUs, though. I first ran across one at age 16, a PDP-8/L, which I still have and still works. It's about the same speed and capacity of the Straight-8, but since it's TTL-based, not transistor-based, is about 1/4 the volume (and a lot fewer amps to run).

EvanK
June 14th, 2008, 10:04 PM
Is this - Im pretty sure its a DEC (says digital equipment corporation on the front in the picture,) does anyone happen to have one of these beauties?

As AHM showed (via BillDeg's pictures), the one you posted is merely an artist's rendering. The actual top-side covers are very dark and you can't see through them very well.

Self-serving note: if you come to the VCF East 5.0 (Sept. 13-14) here in New Jersey then you can see our Straight-8 in person! Of course it will not be operational. We have it on display with period-appropriate accessories -- a Bendix plotter and a Teletype model ASR-33. We also have the manual from SAM-76 which was a programming language for the '8 that was equivalent (in mission) to later languages like BASIC.

Nor was AHM joking about the barn: it sat in the original owner's barn for about 30 years until we rescued it two months ago. Upon a top-level cleaning of the inside, we found an actual mouse nest inside (no sign of the tenant).

One of the dark blue top covers is broken, so we're having replica covers mde by a local plastics fabricator. We will put the other non-broken cover into storage. Our exhibit will have a sign explaining to visitors that the two side covers are not original, but that everything else is original. Since the covers are being custom-designed for us, we'll probably get them a shade or two lighter than the originals, to make them easier to see through (and that way we'll avoid having to constantly open them).

DEC made 1,500 of these. Nobody seems to know how many were the desktop version and how many were the rack-mount version -- not even Gordon Bell knows and he was the product manager! Also many of the desktop versions were converted to rack-mount which confuses it further.

Ours is serial number 1,158. The '8 debuted in 1965 and we assume ours was made in '67 toward the end of production.

It was originally used for a student club here in NJ called the RESISTORS: www.resistors.org

rorypoole
March 8th, 2013, 04:54 PM
how is the pdp8 going?